Video: Reading Time in Minutes and Converting It to Seconds to Compare between the Two

A tutor gives his two students a quiz. The two stopwatches show the time taken by Liam and Jacob to solve the quiz. What is the time taken by each of them, respectively, in seconds? Who finishes the quiz first?

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Video Transcript

A tutor gives his two students a quiz. The two stopwatches show the time taken by Liam and Jacob to solve the quiz. What is the time taken by each of them, respectively, in seconds? Who finishes the quiz first?

This question describes two students, Liam and Jacob, who’ve been given a quiz to do by their tutor. It seems like it was a little bit of a competition because we’re shown two stopwatches which show the time taken by each of these two students to finish the quiz. The first part of our problem asks us to find the time that it takes both Liam and Jacob to solve the quiz in seconds. This word “respectively” here isn’t as complicated as it looks. It just means in the order that they’ve been mentioned. So when we work out both times, we need to say Liam’s time first and then Jacob’s. Now, when both students started the quiz, the stopwatch would’ve looked a little bit like this.

As soon as the tutor started timing, the digits to the right of the two dots would’ve slowly increased, one, two, and so on. These digits show the number of seconds that have gone by. And we know with stopwatches like this, the two digits to the left of the two dots show the number of minutes that have gone by. So we can see straightaway how long each student took. Liam’s stopwatch shows one minute, 10 seconds. And Jacob’s shows one minute, 25 seconds. But there’s a slight problem here because we’re told to give the times in seconds. In other words, we’re gonna have to convert between a time given in minutes and seconds to just seconds.

And to help us, we’re going to have to remember a fact about minutes and seconds. This bar model shows Liam’s time of one minute, 10 seconds. Do you remember how many seconds there are in a minute? One minute is the same as 60 seconds. And 60 seconds plus another 10 seconds equals 70 seconds altogether. And we can use a similar bar model to help convert Jacob’s time into seconds. He took one minute, 25 seconds, which is the same as 60 seconds plus 25 seconds, which is 85 seconds in total. And as we’ve said, we need to give these times in the order that they’re mentioned, so Liam’s time and then Jacob’s.

In the final part of the problem, we’re asked, “Who finishes the quiz first?” And because we’ve converted both times into a number of seconds, we can just compare the numbers. 70 is less than 85. And when we’re talking about time, the quicker we do something, the less time it takes or the less number of seconds it takes. Liam’s taken less time, and so he finishes the quiz first.

This question tested our ability to read digital stopwatches but also how to convert between a time in minutes and seconds to a time just in seconds. We knew that there were 60 seconds in a minute, and this helped us. The time taken by each student to complete the quiz, in seconds, in the order that they’re mentioned, is 70 seconds and 85 seconds. And so we know the student who finishes the quiz first is Liam.

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